What did Charles Townshend invent?

Charles Townshend is responsible for inventing the four-field crop rotation system. Although similar systems had been used in the past in agriculture, Townshend was the first to improve upon it and bring it to Great Britain.

The four-field crop rotation system was devised to allow fields to rest while still growing food. If a crop is continually grown in the same field, the soil will lose nutrients in time and become far less effective. Dividing a large field into four fields and rotating them each season allows the fields to retain high levels of nutrients. Townshend primarily used wheat, clover, oats and turnips in his system.